Stabilized carbon tetrachloride



Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE STABILIZED CARBON TETRACHLQRIDE Edmund C. Missbach, Oakland, Calif., assignor to Stauffer Chemical Company, a corporation of California Serial No. 73,714

2 Claims.

This invention relates to the prevention of decomposition of halogenated hydrocarbon compounds, particularly chlorinated aliphatic hydrocarbons, and to the prevention of corrosion by these compounds. It is known that these materials when exposed to moisture, light, air, and heat, particularly during distillation, as in the case of carbon tetrachloride, decompose with the formation of substances of an objectionable character, usually acidic substances which render the material unsuitable for such purposes as extractions as well as corroding equipment. The decomposition I attribute to hydrolysis and liberation of acid or acid-bodies which also catalyze the decomposition.

Examples of materials with which the present invention is concerned are carbon tetrachloride, CCli, chloroform, CHCls, trichlorethylene, C2HC13, tetrachlorethylene, C2014, pentachlorethylene, CzHCls, and the like. Generally, it is concerned with chlorinated and brominated derivatives of methane, ethane, and higher parafiins, as well as ethylene and higher homologues thereof.

The object of this invention is to provide an effective stabilizer for chlorinated hydrocarbons which need be used only in relatively small concentrations, in effect a negative catalyst for decomposition.

Another object of this invention is to provide an 30 efiective corrosion inhibitor for use in the presv ence of halogenated hydrocarbons.

I have found that numerous compounds hereinafter set forth are effective stabilizers and corrosion inhibitors for these materials. Of course, one inhibitor may not be practical for reasons other than its corrosion inhibiting properties and choice must be exercised to the end in view. For example, an inhibitor in carbon tetrachloride to be used in dry cleaning clothes must not deleteriously afl'ect fabrics to be cleaned or alter the color thereof.

The corrosion inhibitor used need only be present in a relatively small concentration, usually a small fraction of 1%, and compounds of relatively low solubility in the halogenated. hydrocarbon have been used effectively. In some cases, where it is desired to use relatively large quantitles of the inhibitor, and where the water solubility of the corrosion inhibitor is relatively greater than its solubility in the compound, the inhibitor may be introduced in the form of an aqueous solution. Such a mixture is effective particularly during distillation, by stabilizing the halogenated hydrocarbon in its liquid state as well as in the vapor phase, a sufllcient amount of the inhibitor being volatile with the water vapor. By stabilizing amount I refer to a quantity of the order of 1% and less and capable of stabilizing eifectively the material.

In cases where the solubility of the corrosion inhibitor in the halogenated hydrocarbon compound is relatively very small, it has been found that the efiiciency of these particular inhibitors is so great, that only very small quantities of same are required to stabilize the halogenated hydrocarbon compound'to the extent demanded in practice. If it is desired to apply larger proportional amounts of an inhibitor of a solid type, it is reduced to a fine powder, and suspended in the halogenated hydrocarbon, which procedure is especially advisable in case of recovering the halogenated hydrocarbon by distillation.

In some other cases, where it is desired to increase the concentrationof the inhibitor above its solubility in the halogenated compound, it is dissolved in a solvent compound miscible with the halogen compound and then incorporated. As suitable solvents, I have used the following compounds: Ethylal, methylal, n-butyl alcohol, npropyl alcohol, methyl ethyl ketone, allyl alcohol, allylethyl ether, methyl carbonate, ethyl carbonate, ethyl oenanthate, beta dimethylamino-ethyl alcohol, n-heptaldehyde, and polymerized castor oil. In the case of polymerized castor oil, this material appears to have a metal protecting action and reduces the rate of corrosion apparently by forming a protecting film on the metal.

In all cases, where the corrosion inhibitors mentioned are in the form of solid substances, or are liquids at atmospheric temperatures, and have boiling points considerably higher than that of the halogenated hydrocarbon, they are sumciently volatile with the water vapor escaping together with the vapor of the halogenated hy-, drocarbon during distillation. They are therefore not only capable of protecting the latter in the liquid phase, but also in the vapor phase, as have been sufiiciently demonstrated by accelerated corrosion tests made in behalf of these corrosion inhibitors, and conducted continuously for a period of 168 hours under reflux in the presence of water, as well as by use for several years iinder conditions. met in practice with carbon tetrachloride.

This case is a division of my case 3,182 filed January 23, 1935, which in turn is a division of. my case 692,819, filed October 9, 1933, which are incorporated by reference. In this case I claim a group of compounds which can be considered as derived from urea, termed ureides.

Amides of carbonic acid, normal and acid, as carbamide (urea) and carbamic acid, and derivatives of imido-carbonic acid, are useful as are urethane, ethylimido-dicarboxylate, biuret, urils as diurea,' and semi-carbazide or semi-hydrocarbazide, as well as o-phenetyl urea. Alkylated ureas are also useful as the methyl-, ethyl-, and sym.-diethvl, and unsym.-diethyl ureas. Purine, a complex cyclic diureide is included.

Amidines of carbonic acid as guanidine, the isolog of urea and its derivatives, guanidine carbonate, amino-guanidine, as well as glycocy-' This invention, however, is not limited to the use of a single substance or compound mentioned herein,-or which are related to their respectlve class or groups, but I may also employ two or more of these substances in combination with each other, in connection with the stabilimtion oi halogenated hydrocarbons, or I may use a substance which forms a part of certain compounds mentioned herein.

The tests of materials hereinbefore set forth are by way of example only, and are not to be taken as limiting the invention which includes the use of all of those compounds disclosed, as inhibitors for decomposition and corrosion, as well as materials which are merely higher homologues, or derivatives, or substitution products of the disclosed inhibiting compounds.

I claim:

1. Carbon tetrachloride containing a stabilizing amount of a ureide.

2. Carbon tetrachloride containing a stabilizing amount of guanidine.

EDMUND C. IVHSSBACH. 

